A new umbrella group representing various insurgent groups operating in Baluchistan claimed responsibility for an attack on Thursday when 14 passengers were killed after being kidnapped from buses in the province, which borders Iran.

Pakistani Foreign Minister Shah Mahmood Qureshi said on Saturday the training and logistical camps of the new alliance that carried out the attack were inside Iran and called for Iran to take action against the insurgents.

Iranian TV said that Khan began his two-day visit to Iran, the first since he took office last August, with a stop in the northeastern holy Shi’ite city of Mashhad.

Khan will meet Iran’s Supreme Leader Ayatollah Ali Khamenei and President Hassan Rouhani, as well as other officials, in Tehran on Monday.

Relations between Iran and Pakistan have been strained in recent months, with both sides accusing each other of not doing enough to stamp out militants allegedly sheltering across the border.

Shi’ite Muslim Iran says militant groups operate from safe havens in Pakistan and has repeatedly called on Islamabad to crack down on them.

Tehran has stepped up security along its long border with Pakistan after a suicide bomber killed 27 members of Iran’s elite Revolutionary Guards in mid-February in southeastern Iran, with Iranian officials saying the attackers were based inside Pakistan.

The Sunni group Jaish al Adl (Army of Justice), which says it seeks greater rights and better living conditions for the ethnic Baloch minority, claimed responsibility for that attack.